diff --git a/pkg/personality/traits.go b/pkg/personality/traits.go
new file mode 100644
index 0000000..821eddf
--- /dev/null
+++ b/pkg/personality/traits.go
@@ -0,0 +1,53 @@
+package personality
+
+import "time"
+
+type Trait string
+
+const (
+	TraitHumor       Trait = "humor"
+	TraitCuriosity   Trait = "curiosity"
+	TraitPlayfulness Trait = "playfulness"
+	TraitFormality   Trait = "formality"
+	TraitAffection   Trait = "affection"
+)
+
+type TraitValue struct {
+	Trait     Trait     `json:"trait"`
+	Value     float64   `json:"value"`
+	MinValue  float64   `json:"minValue"`
+	MaxValue  float64   `json:"maxValue"`
+	UpdatedAt time.Time `json:"updatedAt"`
+}
+
+type PersonalityProfile struct {
+	Traits    []TraitValue `json:"traits"`
+	UpdatedAt time.Time    `json:"updatedAt"`
+}
+
+type RelationshipMetrics struct {
+	Familiarity  float64   `json:"familiarity"`
+	Trust        float64   `json:"trust"`
+	SharedTopics []string  `json:"sharedTopics"`
+	InsideJokes  []string  `json:"insideJokes"`
+	UpdatedAt    time.Time `json:"updatedAt"`
+}
+
+type DiaryEntry struct {
+	ID           string    `json:"id"`
+	Date         string    `json:"date"` // YYYY-MM-DD
+	Summary      string    `json:"summary"`
+	Mood         string    `json:"mood"`
+	Topics       []string  `json:"topics"`
+	Observations []string  `json:"observations"`
+	CreatedAt    time.Time `json:"createdAt"`
+}
+
+type Observation struct {
+	ID         string    `json:"id"`
+	Content    string    `json:"content"`
+	Confidence float64   `json:"confidence"`
+	Category   string    `json:"category"`
+	Applied    bool      `json:"applied"`
+	CreatedAt  time.Time `json:"createdAt"`
+}
diff --git a/pkg/types/types.go b/pkg/types/types.go
new file mode 100644
index 0000000..d06c187
--- /dev/null
+++ b/pkg/types/types.go
@@ -0,0 +1,44 @@
+package types
+
+import "time"
+
+type Role string
+
+const (
+	RoleUser      Role = "user"
+	RoleAssistant Role = "assistant"
+	RoleSystem    Role = "system"
+	RoleTool      Role = "tool"
+)
+
+type Message struct {
+	ID        string    `json:"id"`
+	Role      Role      `json:"role"`
+	Content   string    `json:"content"`
+	ToolCall  *ToolCall `json:"toolCall,omitempty"`
+	CreatedAt time.Time `json:"createdAt"`
+}
+
+type ToolCall struct {
+	Name      string `json:"name"`
+	Arguments string `json:"arguments"`
+	Result    string `json:"result,omitempty"`
+}
+
+type Conversation struct {
+	ID        string    `json:"id"`
+	Messages  []Message `json:"messages"`
+	CreatedAt time.Time `json:"createdAt"`
+	UpdatedAt time.Time `json:"updatedAt"`
+}
+
+type Mood string
+
+const (
+	MoodNeutral    Mood = "neutral"
+	MoodCurious    Mood = "curious"
+	MoodPlayful    Mood = "playful"
+	MoodThoughtful Mood = "thoughtful"
+	MoodAnnoyed    Mood = "annoyed"
+	MoodTired      Mood = "tired"
+)